During two intervals in 1999, simultaneous observations of Jupiter's decametric and hectometric radio emissions were made with the Cassini radio and plasma wave instrument (RPWS) and the radio and plasma wave instrument (WAVES) on the Wind spacecraft in Earth orbit. During January the Jovian longitude difference between the two spacecraft was about 5¿, whereas for the August-September Earth flyby of Cassini, the angle ranged from 0¿ to about 2.5¿ (the Jovicentric latitudinal difference was <0.3¿ during both intervals). With these separations the instantaneous widths of the walls of the hollow conical radiation beams of some of the decametric arcs were measured by cross correlating dynamic spectra. The results suggest that the typical width is approximately 1.5¿¿0.5¿. The conical beams seem to move at Io's revolution rate for Io-controlled arcs. Additionally, some of the nonarc hectometric wavelength emissions show some properties of both wide and very narrow beam widths.